Homeodomain protein CDX2 regulates goblet-specific MUC2 gene expression

Silibinin modulates caudal-type homeobox transcription factor (CDX2), an intestine specific tumor suppressor to abrogate colon cancer in experimental rats

To authenticate the colon cancer preventive potential of silibinin, the efficacy of silibinin needs to be tested by evaluating an organ-specific biomarker. The aim of this study was to evaluate the impact of silibinin on the colonic expression of the caudal-type homeobox transcription factor (CDX2) an intestine specific tumor suppressor gene and its downstream targets in the colon of rats challenged with 1,2 dimethyl hydrazine (DMH). Rats of groups 1 and 2 were treated as control and silibinin control. Rats under groups 3 and 4 were given DMH (20 mg/kg body weight (b.w.) subcutaneously) once a week for 15 consecutive weeks from the 4th week of the experimental period. In addition, group 4 rats alone were treated with silibinin (50 mg/kg b.w. per os) everyday throughout the study period of 32 weeks. Histological investigation and messenger RNA and protein expression studies were performed in the colonic tissues of experimental rats. Findings of the study revealed that DMH administration significantly decreased the expression of CDX2 and Guanylyl cyclase C ( GCC) in the colon of experimental rats. Further the decreased levels of CDX2 protein, colonic mucin content, and increased number of mast cells in the colon of DMH alone-administered rats reflects the onset of carcinogenesis. The pathological changes caused due to CDX2 suppression were attenuated by silibinin supplementation.

Expression of MUC2, MUC5AC, MUC5B, and MUC6 mucins in colorectal cancers and their association with the CpG island methylator phenotype

Mucinous differentiation is associated with both CpG island methylator phenotype and microsatellite instability in colorectal cancer. The mucinous phenotype derives from abundant expression of the colonic goblet cell mucin, MUC2, and de novo expression of gastric foveolar mucin, MUC5AC. We, therefore, investigated the protein expression levels of MUC2 and MUC5AC, as well as MUC5B and MUC6, in molecular subtypes of colorectal cancer. Seven-hundred and twenty-two incident colorectal carcinomas occurring in 702 participants of the Melbourne Collaborative Cohort Study were characterized for methylator status, MLH1 methylation, somatic BRAF and KRAS mutations, microsatellite-instability status, MLH1, MSH2, MSH6, and PMS2 mismatch repair, and p53 protein expression, and their histopathology was reviewed. Protein expression levels of MUC2, MUC5AC, MUC5B, MUC6, and the putative mucin regulator CDX2 were compared with molecular and clinicopathological features of colorectal cancers using odds ratios and corresponding 95% confidence intervals. MUC2 overexpression (>25% positive tumor cells) was observed in 33% colorectal cancers, MUC5B expression in 53%, and de novo MUC5AC and MUC6 expression in 50% and 39%, respectively. Co-expression of two or more of the mucins was commonly observed. Expression of MUC2, MUC5AC and MUC6 was strongly associated with features associated with tumorigenesis via the serrated neoplasia pathway, including methylator positivity, somatic BRAF p.V600E mutation, and mismatch repair deficiency, as well as proximal location, poor differentiation, lymphocytic response, and increased T stage (all P<0.001). Overexpression was observed in tumors with and without mucinous differentiation. There were inverse associations between expression of all four mucins and p53 overexpression. CDX2 expression was inversely associated with MUC2, MUC5AC and MUC6 expression. Our results suggest that, in methylator-positive tumors, mucin genes on chromosome 11p15.5 region undergo increased expression via mechanisms other than direct regulation by CDX2.

Virulent Shigella flexneri affects secretion, expression, and glycosylation of gel-forming mucins in mucus-producing cells

Mucin glycoproteins are secreted in large amounts by the intestinal epithelium and constitute an efficient component of innate immune defenses to promote homeostasis and protect against enteric pathogens. In this study, our objective was to investigate how the bacterial enteropathogen Shigella flexneri, which causes bacillary dysentery, copes with the mucin defense barrier. We report that upon in vitro infection of mucin-producing polarized human intestinal epithelial cells, virulent S. flexneri manipulates the secretion of gel-forming mucins. This phenomenon, which is triggered only by virulent strains, results in accumulation of mucins at the cell apical surface, leading to the appearance of a gel-like structure that favors access of bacteria to the cell surface and the subsequent invasion process. We identify MUC5AC, a gel-forming mucin, as a component of this structure. Formation of this gel does not depend on modifications of electrolyte concentrations, induction of trefoil factor expression, endoplasmic reticulum stress, or response to unfolded proteins. In addition, transcriptional and biochemical analyses of infected cells reveal modulations of mucin gene expression and modifications of mucin glycosylation patterns, both of which are induced by virulent bacteria in a type III secretion system-dependent manner. Thus, S. flexneri has developed a dedicated strategy to alter the mucus barrier by targeting key elements of the gel-forming capacity of mucins: gene transcription, protein glycosylation, and secretion.

Loss of MUC2 expression predicts disease recurrence and poor outcome in colorectal carcinoma

Clinical staging and histological grading after surgery have been the "gold standard" for predicting prognosis and planning for adjuvant therapy of colorectal cancer (CRC). With the recent development of molecular markers, it has become possible to characterize tumors at the molecular level. This is important for stage II and III CRCs, in which clinicopathological features do not accurately predict heterogeneity, e.g., in their tumor response to adjuvant therapy. In the present study, archival samples from 141 patients with stage I, II, III, or IV CRC treated during 1981-1990 at Turku University Hospital (Finland) were used (as microarray blocks) to analyze MUC2 expression by immunohistochemistry. Altogether, 49.7 % of all tumors were positive for MUC2. There was no significant correlation between MUC2 expression and age (P < 0.499), tumor invasion (P < 0.127), tumor staging (P < 0.470), histological grade (P < 0.706), lymph node involvement (P < 0.854), or tumor metastasis (P < 0.586). However, loss of MUC2 expression was significantly associated with disease recurrence (P < 0.031), tumor localization (P < 0.048), and with borderline significance with gender (P < 0.085). In univariate (Kaplan-Meier) survival analysis, positive MUC2 significantly predicted longer disease-free survival (DFS) and disease-specific survival (DSS) as well. However, in multivariate (Cox) survival analysis, MUC2 lost its power as an independent predictor of DFS and DSS. Our results implicate the value of MUC2 expression in predicting disease recurrence and long-term survival in CRC.

Identification of an intestine-specific promoter and inducible expression of bacterial α-galactosidase in mammalian cells by a lac operon system

Background

α-galactosidase has been widely used in animal husbandry to reduce anti-nutritional factors (such as α-galactoside) in feed. Intestine-specific and substrate inducible expression of α-galactosidase would be highly beneficial for transgenic animal production.

Methods

To achieve the intestine-specific and substrate inducible expression of α-galactosidase, we first identified intestine-specific promoters by comparing the transcriptional activity and tissue specificity of four intestine-specific promoters from human intestinal fatty acid binding protein, rat intestinal fatty acid binding protein, human mucin-2 and human lysozyme. We made two chimeric constructs combining the promoter and enhancer of human mucin-2, rat intestinal trefoil factor and human sucrase-isomaltase. Then a modified lac operon system was constructed to investigate the induction of α-galactosidase expression and enzyme activity by isopropyl β-D-1-thiogalactopyranoside (IPTG) and an α-galactosidase substrate, α-lactose.

We declared that the research carried out on human (Zhai Yafeng) was in compliance with the Helsinki Declaration, and experimental research on animals also followed internationally recognized guidelines.

Results

The activity of the human mucin-2 promoter was about 2 to 3 times higher than that of other intestine-specific promoters. In the lac operon system, the repressor significantly decreased (P < 0.05) luciferase activity by approximately 6.5-fold and reduced the percentage of cells expressing green fluorescent protein (GFP) by approximately 2-fold. In addition, the expression level of α-galactosidase mRNA was decreased by 6-fold and α-galactosidase activity was reduced by 8-fold. In line with our expectations, IPTG and α-lactose supplementation reversed (P < 0.05) the inhibition and produced a 5-fold increase of luciferase activity, an 11-fold enhancement in the percentage of cells with GFP expression and an increase in α-galactosidase mRNA abundance (by about 5-fold) and α-galactosidase activity (by about 7-fold).

Conclusions

We have successfully constructed a high specificity inducible lac operon system in an intestine-derived cell line, which could be of great value for gene therapy applications and transgenic animal production.

Type 2 cGMP-dependent protein kinase regulates proliferation and differentiation in the colonic mucosa

Signaling through cGMP has emerged as an important regulator of tissue homeostasis in the gastrointestinal tract, but the mechanism is not known. Type 2 cGMP-dependent protein kinase (PKG2) is a major cGMP effector in the gut epithelium, and the present studies have tested its importance in the regulation of proliferation and differentiation in the mouse colon and in colon cancer cell lines. Tissue homeostasis was examined in the proximal colon of Prkg2(-/-) mice using histological markers of proliferation and differentiation. The effect of ectopic PKG2 on proliferation and differentiation was tested in vitro using inducible colon cancer cell lines. PCR and luciferase reporter assays were used to determine the importance of Sox9 downstream of PKG2. The colons of Prkg2(-/-) mice exhibited crypt hyperplasia, increased epithelial apoptosis, and reduced numbers of differentiated goblet and enteroendocrine cells. Ectopic PKG2 was able to inhibit proliferation and induce Muc2 and CDX2 expression in colon cancer cells, but did not significantly affect cell death. PKG2 reduced Sox9 levels and signaling, suggesting possible involvement of this pathway downstream of cGMP in the colon. The work presented here demonstrates a novel antiproliferative and prodifferentiation role for PKG2 in the colon. These homeostatic functions of PKG2 were reproducible in colon cancer cells lines where downregulation of Sox9 is a possible mechanism. The similarities in phenotype between PKG2 and GCC knockout mice positions PKG2 as a likely mediator of the homeostatic effects of cGMP signaling in the colon.

Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus

Cdx2 expression in esophageal stem cells induced by reflux bile acids may be an important factor for development of Barrett's esophagus, whereas Notch signaling is a molecular signaling pathway that plays an important role in the determination of cell differentiation. ATOH1 (a factor associated with Notch signaling) plays an important role in differentiation of stem cells into goblet cells. However, the relationship between the Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus has not been explored. The aim of this study was to investigate the interrelationship between Notch signaling and Cdx2 in esophageal epithelial cells. The expressions of Cdx2, MUC2, and intracellular signaling molecules related to Notch signaling (Notch1, Hes1, and ATOH1) were examined using real-time polymerase chain reaction (PCR) and immunohistochemical staining with biopsy specimens obtained from esophageal intestinal metaplasia (IM) with goblet cells (IM⁺) and columnar epithelium not accompanied by goblet cells (IM⁻). For in vitro experiments, we employed human esophageal epithelial cell lines (OE33, OE19, and Het-1A). After forced Cdx2 expression by applying a Cdx2 expression vector to the cells, changes in the expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 were analyzed by real-time PCR and western blot analysis. Changes in expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 in cells were analyzed following stimulation with bile acids in the presence or absence of Cdx2 blocking with Cdx2-siRNA. Suppressed Hes1 and enhanced ATOH1 and MUC2 expressions were identified in IM⁺ specimens. Forced expression of Cdx2 in cells suppressed Hes1, and enhanced ATOH1 and MUC2 expressions, whereas bile acids suppressed Hes1, and enhanced ATOH1, Cdx2, and MUC2 expressions. On the other hand, these effects were blocked by siRNA-based Cdx2 downregulation. Enhanced expression of Cdx2 by stimulation with bile acids may induce intestinal differentiation of esophageal columnar cells by interaction with the Notch signaling pathway.

Transcription factors c-Myc and CDX2 mediate E-selectin ligand expression in colon cancer cells undergoing EGF/bFGF-induced epithelial-mesenchymal transition

Sialyl Lewis x (sLe(x)) and sialyl Lewis a (sLe(a)) glycans are expressed on highly metastatic colon cancer cells. They promote extravasation of cancer cells and tumor angiogenesis via interacting with E-selectin on endothelial cells. Recently, epithelial-mesenchymal transition (EMT) has been noted as a critical phenotypic alteration in metastatic cancer cells. To address the association between sLe(x/a) expression and EMT, we assessed whether sLe(x/a) are highly expressed on colon cancer cells undergoing EMT. Treatment of HT29 and DLD-1 cells with EGF and/or basic FGF (bFGF) induced EMT and significantly increased sLe(x/a) expression resulting in enhanced E-selectin binding activity. The transcript levels of the glycosyltransferase genes ST3GAL1/3/4 and FUT3 were significantly elevated and that of FUT2 was significantly suppressed by the treatment. We provide evidence that ST3GAL1/3/4 and FUT3 are transcriptionally up-regulated by c-Myc with probable involvement of Ser62 phosphorylation, and that FUT2 is transcriptionally down-regulated through the attenuation of CDX2. The contribution of c-Myc and CDX2 to the sLe(x/a) induction was proved to be significant by knockdown or forced expression experiments. Interestingly, the cells undergoing EMT exhibited significantly increased VEGF secretion, which can promote tumor angiogenesis in cooperation with sLe(x/a). Finally, immunohistological study indicated high E-selectin ligand expression on cancer cells undergoing EMT in vivo, supporting their coexistence observed in vitro. These results suggest a significant link between sLe(x/a) expression and EMT in colon cancer cells and a pivotal role of c-Myc and CDX2 in regulating sLe(x/a) expression during EMT.

TNF-α-induced down-regulation of CDX2 suppresses MEP1A expression in colitis

BACKGROUND/AIMS

High levels of pro-inflammatory cytokines are linked to inflammatory bowel disease (IBD). The transcription factor Caudal-related homeobox transcription factor 2 (CDX2) plays a crucial role in differentiation of intestinal epithelium and regulates IBD-susceptibility genes, including meprin 1A (MEP1A). The aim was to investigate the expression of CDX2 and MEP1A in colitis; to assess if they are regulated by tumor necrosis factor-α (TNF-α), and finally to reveal if CDX2 is involved in a TNF-α-induced down-regulation of MEP1A.

METHODS

Expression of CDX2 and MEP1A was investigated in colonic biopsies of ulcerative colitis (UC) patients and in dextran sodium sulfate (DSS)-induced colitis. CDX2 protein expression was investigated by immunoblotting and immunohistochemical procedures. CDX2 and MEP1A regulation was examined in TNF-α-treated Caco-2 cells by reverse transcription-polymerase chain reaction and with reporter gene assays, and the effect of anti-TNF-α treatment was assessed using infliximab. Finally, in vivo CDX2-DNA interactions were investigated by chromatin immunoprecipitation.

RESULTS

The CDX2 and MEP1A mRNA expression was significantly decreased in active UC patients and in DSS-colitis. Colonic biopsy specimens from active UC showed markedly decreased CDX2 staining. TNF-α treatment diminished the CDX2 and MEP1A mRNA levels, a decrease which, was counteracted by infliximab treatment. Reporter gene assays showed significantly reduced CDX2 and MEP1A activity upon TNF-α stimulation. Finally, TNF-α impaired the ability of CDX2 to interact and activate its own, as well as the MEP1A expression.

CONCLUSIONS

The present results indicate that a TNF-α-mediated down-regulation of CDX2 can be related to suppressed expression of MEP1A during intestinal inflammation.

Inflammatory cues modulate the expression of secretory product genes, Golgi sulfotransferases and sulfomucin production in LS174T cells

The signals that mediate goblet cell expression of specific mucin chemotypes are poorly defined. Animal and in vitro studies show that acidomucin chemotypes may be altered by inflammation and changes in intestinal microbiota. To examine factors that may elicit this response, human adenocarcinoma-derived LS174T cells, which have a goblet cell-like phenotype and produce both sulfo- and sialomucins, were used to examine the effects of selected microbial and host factors on expression of goblet cell secretory product genes, sulfotransferases and sulfomucin production. Expression of genes encoding mucin 2 (MUC2), resistin-like molecule β (RETNLB), and trefoil factor 3 (TFF3) and Golgi sulfotransferases, carbohydrate (N-acetylglucosamine 6-O) sulfotransferase 5 (CHST5) and galactose-3-O-sulfotransferase 2 (GAL3ST2), was measured by quantitative reverse transcriptase-polymerase chain reaction following treatment with bacterial flagellin, tumor necrosis factor α (TNF-α) or the mucogenic cytokine interleukin-13 (IL-13). Expression of the toll-like receptor 5 (TLR5) gene was also analysed. Sulfomucin expression was examined via high-iron diamide/alcian blue (HID/AB) histochemistry and immunofluorescent staining for the Sulfo Le(a) antigen, which is synthesized in part by GAL3ST2. Flagellin, IL-13 and TNF-α all significantly increased GAL3ST2, MUC2, TFF3 and TLR5 expression, while only IL-13 increased RETNLB and CHST5 expression. Based on HID/AB histochemistry, mucin sulfation was significantly increased in response to both flagellin and IL-13 but not TNF-α. Only treatment with flagellin increased the expression of the Sulfo Le(a) antigen. Collectively, these results indicate that bacterial flagellin, IL-13 and TNF-α differentially modulate the expression of goblet cell secretory product genes, sulfotransferases and sulfomucin production.

Aberrant expression of intelectin-1 in gastric cancer: its relationship with clinicopathological features and prognosis

PURPOSES

Human intelectin-1 (ITLN-1) is a novel identified galactose-binding lectin that is expressed in the colonic goblet cells. Since gastric adenocarcinomas can arise through a process of intestinalization, we speculate that ITLN-1 may be aberrantly expressed in gastric cancer. This study was undertaken to examine the ITLN-1 expression in gastric cancer and correlate it with clinical outcomes.

METHODS

One hundred and ninety-six gastric cancer patients were evaluated for the ITLN-1 expression by immunohistochemistry. The ITLN-1 transcripts were measured by real-time quantitative PCR.

RESULTS

ITLN-1 expression was absent in normal gastric mucosa, whereas areas of intestinal metaplasia revealed ITLN-1 immunoreactivity. One hundred and forty-two gastric cancer patients (72.4%) were positive for ITLN-1 expression. In a subtotal of 20 patients, ITLN-1 transcripts were significantly enhanced in gastric cancer tissues than in normal gastric mucosa (P < 0.001). The expression rate of ITLN-1 was higher in intestinal-type carcinomas than in diffuse-type carcinomas (P = 0.003). ITLN-1 positivity in gastric cancer was positively correlated with tumor differentiation (P = 0.001) and CDX2 expression (P < 0.001), and inversely correlated with depth of invasion (P = 0.007), lymph node metastasis (P = 0.001), distant metastasis (P = 0.014), clinical stage (P = 0.006), Ki-67 expression (P = 0.001), and heparanase expression (P < 0.001), without correlation with age, gender, tumor location, or tumor size. In univariate and multivariate analyses, ITLN-1 was an independent prognostic factor for longer survival of gastric cancer patients (P = 0.001).

CONCLUSION

The aberrant ITLN-1 expression in gastric cancer is correlated with clinicopathological features and may be a useful prognostic factor for predicting the outcomes of gastric cancer patients.

Tumor necrosis factor receptor 1-dependent depletion of mucus in immature small intestine: a potential role in neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in premature infants. NEC is believed to occur when intestinal bacteria invade the intestinal epithelial layer, causing subsequent inflammation and tissue necrosis. Mucins are produced and secreted by epithelial goblet cells as a key component of the innate immune system and barrier function of the intestinal tract that help protect against bacterial invasion. To better understand the role of mucins in NEC, we quantified the number of mucus-containing small intestinal goblet cells present in infants with NEC and found they had significantly fewer goblet cells and Paneth cells compared with controls. To test whether inflammation has a developmentally dependent effect on intestinal goblet cells, TNF-α was injected into mice at various stages of intestinal development. TNF-α caused a loss of mucus-containing goblet cells only in immature mice and induced Muc2 and Muc3 mRNA upregulation only in mature ileum. Only minimal changes were seen in apoptosis and in expression of markers of goblet cell differentiation. TNF-α increased small intestinal mucus secretion and goblet cell hypersensitivity to prostaglandin E2 (PGE(2)), a known mucus secretagogue produced by macrophages. These TNF-α-induced changes in mucus mRNA levels required TNF receptor 2 (TNFR2), whereas TNF-α-induced loss of mucus-positive goblet cells required TNFR1. Our findings of developmentally dependent TNF-α-induced alterations on intestinal mucus may help explain why NEC is predominantly found in premature infants, and TNF-α-induced alterations of the intestinal innate immune system and barrier functions may play a role in the pathogenesis of NEC itself.

The relationship among PDX1, CDX2, and mucin profiles in gastric carcinomas; correlations with clinicopathologic parameters

PURPOSE

Several studies performed on pancreatic-duodenal homeobox 1 (PDX1) have demonstrated a loss of expression and negative tumor modulator effect in gastric carcinoma. Relations between PDX1 and gastric metaplasia, differentiated type of gastric carcinoma, and the early stage of the disease have been exhibited in previous reports. The aim of this study was to examine expressions of PDX1, caudal type homeobox 2 (CDX2) and mucin (MUC) profiles to address the role of PDX1 in gastric carcinogenesis and its relationship with CDX2.

METHODS

Seventy gastrectomy specimens were analyzed immunohistochemically for PDX1, CDX2, MUC2, MUC5AC, and MUC6 expressions. The sum of cytoplasmic and nuclear PDX1 immunostaining and PDX1 positivity were assessed. All of the antibodies were examined for a correlation with tumor type, clinicopathologic parameters, and metaplasias. The relation of Ki-67 proliferation index with the expression profiles was also investigated.

RESULTS

Neither PDX1 (66/70) nor CDX2 (37/70) and the mucin profiles (MUC2:11/70, MUC5AC:48/70, MUC6:41/70) showed a significant difference between differentiated and undifferentiated types of gastric carcinoma and clinicopathologic parameters. The PDX1 expression frequency was 94.3%, with an average PDX1 score of 8.8 ± 4.2. PDX1 and CDX2 expression showed a significant difference (P = 0.026 and P = 0.002, respectively) among the phenotypic classification of gastric carcinomas. All of the gastric and intestinal mixed-phenotype gastric carcinomas (GI-type) showed both PDX1 and CDX2 immunopositivity. Except for the relation of PDX1 score with MUC6 expression, no significant difference was detected between PDX1 and CDX2, MUC2, and MUC5AC expressions. A relationship between CDX2 and MUC2 and also between MUC5AC and MUC6 was found statistically. The Ki-67 proliferation index revealed a significant positive correlation with PDX1, CDX2, and MUC2 positivity.

CONCLUSIONS

PDX1 expression revealed a higher positivity in gastric carcinomas than the previous studies and showed no relation with tumor type, clinicopathologic parameters, CDX2 expression, or mucin profiles. However, a significant relation of PDX1 and CDX2 expressions among phenotypic classification of gastric carcinomas reveals an idea about similar functions for PDX1 and CDX2 in the evolution of gastric carcinoma.

The dichotomy in carcinogenesis of the distal esophagus and esophagogastric junction: intestinal-type vs cardiac-type mucosa-associated adenocarcinoma

Adenocarcinoma of the distal esophagus and esophagogastric junction continues to rise in incidence. An intestinal metaplasia (Barrett esophagus)-dysplasia-carcinoma sequence induced by gastroesophageal reflux disease is well established. However, a significant number of adenocarcinomas in the vicinity of the esophagogastric junction are seen in the background of gastric/cardiac-type mucosa without intestinal metaplasia. Thus, the aim of this study was to investigate the role of Barrett esophagus (intestinal-type mucosa) in the classification and prognosis of tumors of the distal esophagus and esophagogastric junction. Clinicopathological and molecular characteristics were examined in 157 consecutively resected adenocarcinomas of the distal esophagus and esophagogastric junction and were compared between tumors arising in association with intestinal-type and cardiac-type mucosa. Intestinal-type mucosa-associated adenocarcinomas were more likely to be associated with younger age (P=0.0057), reflux symptoms (P<0.0001), proximal location (P=0.0009), lower T stage (P<0.0001), fewer nodal metastases (P=0.0001), absence of lymphatic (P<0.0001), venous (P=0.0060) or perineural (P<0.0001) invasion. Histologically, intestinal-type mucosa-associated tumors were more likely to be low-grade glandular tumors (P=0.0095) of intestinal or mixed immunophenotype (P=0.015) and express nuclear β-catenin (P=0.0080), whereas tumors arising in a background of cardiac-type mucosa were more frequently associated with EGFR amplification (P=0.0051). Five-year overall survival rate was significantly higher in patients with intestinal-type mucosa-associated tumors (28 vs 9%, P=0.0015), although no survival benefit was seen after adjusting for potential confounders. Our findings support the theory that multiple distinct pathways of tumorigenesis exist in the vicinity of the esophagogastric junction, including one in which tumors arise from dysplastic intestinal metaplasia (intestinal pathway), and one potentially involving dysplasia of the cardiac-type mucosa (non-intestinal pathway). Additional studies are warranted to further clarify their pathogenesis and the molecular mechanisms involved.

BabA-mediated adherence is a potentiator of the Helicobacter pylori type IV secretion system activity

Chronic infection of Helicobacter pylori in the stomach mucosa with translocation of the bacterial cytotoxin-associated gene A (CagA) effector protein via the cag-Type IV secretion system (TFSS) into host epithelial cells are major risk factors for gastritis, gastric ulcers, and cancer. The blood group antigen-binding adhesin BabA mediates the adherence of H. pylori to ABO/Lewis b (Le(b)) blood group antigens in the gastric pit region of the human stomach mucosa. Here, we show both in vitro and in vivo that BabA-mediated binding of H. pylori to Le(b) on the epithelial surface augments TFSS-dependent H. pylori pathogenicity by triggering the production of proinflammatory cytokines and precancer-related factors. We successfully generated Le(b)-positive cell lineages by transfecting Le(b)-negative cells with several glycosyltransferase genes. Using these established cell lines, we found increased mRNA levels of proinflammatory cytokines (CCL5 and IL-8) as well as precancer-related factors (CDX2 and MUC2) after the infection of Le(b)-positive cells with WT H. pylori but not with babA or TFSS deletion mutants. This increased mRNA expression was abrogated when Le(b)-negative cells were infected with WT H. pylori. Thus, H. pylori can exploit BabA-Le(b) binding to trigger TFSS-dependent host cell signaling to induce the transcription of genes that enhance inflammation, development of intestinal metaplasia, and associated precancerous transformations.

MiR-9 downregulates CDX2 expression in gastric cancer cells

Ectopic expression of CDX2, a caudal-related homeobox protein, is known to be associated with the development of intestinal metaplasia in the stomach and gastric carcinogenesis. Previously, we reported that DNA methylation was partly responsible for CDX2 silencing in gastric cancer (GC). However, the mechanism underlying the aberrant expression of CDX2 during malignant transformation remained unclear. MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional regulators. To elucidate the role of miRNAs in CDX2 downregulation in GC cells, putative miRNAs, such as miR-9, were computationally predicted. After exogenous pre-miR-9 precursor transfection, the luciferase activity of a reporter vector containing a part of the 3'-UTR of CDX2 was downregulated in HEK-293T cells. The inverse correlation between the miR-9 and CDX2 protein levels was demonstrated in GC cell lines. By means of miR-9 overexpression and knockdown techniques, the expression levels of the CDX2 protein and downstream target genes (p21, MUC2 and TFF3) were responsively altered in MKN45 and NUGC-3 cells. Transfection of an anti-miR-9 molecule significantly inhibited cell growth by promoting G(1) cell cycle arrest in MKN45 cells similarly to the effect of CDX2 overexpression. Moreover, examination of the miR-9 levels in primary GC tissues revealed that the amounts of miR-9 in the CDX2-negative group were significantly higher than those in the CDX2-positive group (p = 0.004). Therefore, miR-9 might repress CDX2 expression via the binding site in the 3'-UTR, resulting in the promotion of cell proliferation in GCs.

The predominant expression of hepatocyte nuclear factor 4α (HNF4α) in thyroid transcription factor-1 (TTF-1)-negative pulmonary adenocarcinoma

AIMS

To investigate TTF-1-negative pulmonary adenocarcinoma, focusing upon mucin production and the expression of hepatocyte nuclear factor-4α (HNF4α).

MATERIALS AND METHODS

Two hundred and sixty-two cases of pulmonary adenocarcinoma were examined histologically and immunohistochemically; TTF-1 was expressed in 222 cases (84.7%), and 40 cases (15.3%) were negative. Among TTF-1-negative cases there were 31 mucinous-type tumours, and HNF4α, MUC5AC and MUC2 were expressed in 34 cases (85%), 29 cases (72.5%) and four cases (10%), respectively. In contrast, their expression was rare in TTF-1-positive tumours. A statistically inverse correlation was confirmed between the expression of TTF-1 and that of HNF4α and MUC5AC.

CONCLUSION

Most TTF-1-negative pulmonary adenocarcinomas are mucinous lesions with the predominant expression of HNF4α and MUC5AC.

The role of CDX2 in intestinal homeostasis and inflammation

Many transcription factors are known to control transcription at several promoters, while others are only active at a few places. However, due to their importance in controlling cellular functions, aberrant transcription factor function and inappropriate gene regulation have been shown to play a causal role in a large number of diseases and developmental disorders. Inflammatory bowel disease (IBD) is characterized by a chronically inflamed mucosa caused by dysregulation of the intestinal immune homeostasis. The aetiology of IBD is thought to be a combination of genetic and environmental factors, including luminal bacteria. The Caudal-related homeobox transcription factor 2 (CDX2) is critical in early intestinal differentiation and has been implicated as a master regulator of the intestinal homeostasis and permeability in adults. When expressed, CDX2 modulates a diverse set of processes including cell proliferation, differentiation, cell adhesion, migration, and tumorigenesis. In addition to these critical cellular processes, there is increasing evidence for linking CDX2 to intestinal inflammation. The aim of the present paper was to review the current knowledge of CDX2 in regulation of the intestinal homeostasis and further to reveal its potential role in inflammation.

Comparison of six immunohistochemical markers for the histologic diagnosis of neoplasia in Barrett's esophagus

In esophageal neoplasms, the histopathologic differentiation between Barrett's esophagus with or without intraepithelial neoplasia and adenocarcinoma is often challenging. Immunohistochemistry might help to differentiate between these lesions. The expression of CDX2, LI-cadherin, mucin 2 (MUC2), blood group 8 (BG8, Lewis(y)), claudin-2, and villin was investigated in normal gastroesophageal (n = 23) and in Barrett's (n = 17) mucosa, in low-grade (n = 12) and high-grade (n = 9) intraepithelial neoplasia (IEN) as well as in esophageal adenocarcinoma (n = 16), using immunohistochemistry. For CDX2 and LI-cadherin, the immunoreactivity score was highest in IEN while for MUC2, BG8, and villin, it dropped gradually from Barrett's via IEN to adenocarcinoma, and expression of Claudin-2 was only weak and focal in all lesions. The expression of MUC2 and LI-cadherin differed significantly between all examined lesions except between low-grade and high-grade IEN. MUC2 and LI-cadherin are useful immunohistochemical markers for the differentiation between normal glandular mucosa, Barrett's mucosa, IEN, and invasive carcinoma of the esophagus; however, none of the examined markers was helpful for the differentiation between low-grade and high-grade IEN.

CDX2 regulates multidrug resistance 1 gene expression in malignant intestinal epithelium

The caudal-related homeobox transcription factor CDX2 has a key role in intestinal development and differentiation. CDX2 heterozygous mutant mice develop colonic polyps, and loss of CDX2 expression is seen in a subset of colon carcinomas in humans. Ectopic CDX2 expression in the stomach of transgenic mice promotes intestinal metaplasia, and CDX2 expression is frequently detected in intestinal metaplasia in the stomach and esophagus. We sought to define CDX2-regulated genes to enhance knowledge of CDX2 function. HT-29 colorectal cancer cells have minimal endogenous CDX2 expression, and HT-29 cells with ectopic CDX2 expression were generated. Microarray-based gene expression studies revealed that the Multidrug Resistance 1 (MDR1/P-glycoprotein/ABCB1) gene was activated by CDX2. Evidence that the MDR1 gene was a direct transcriptional target of CDX2 was obtained, including analyses with MDR1 reporter gene constructs and chromatin immunoprecipitation assays. RNA interference-mediated inhibition of CDX2 decreased endogenous MDR1 expression. In various colorectal cancer cell lines and human tissues, endogenous MDR1 expression was well correlated to CDX2 expression. Overexpression of CDX2 in HT-29 cells revealed increased resistance to the known substrate of MDR1, vincristine and paclitaxel, which was reversed by an MDR1 inhibitor, verapamil. These data indicate that CDX2 directly regulates MDR1 gene expression through binding to elements in the promoter region. Thus, CDX2 is probably important for basal expression of MDR1, regulating drug excretion and absorption in the lower gastrointestinal tract, as well as for multidrug resistance to chemotherapy reagent in CDX2-positive gastrointestinal cancers.

Immunostaining of gastric cancer with neuroendocrine differentiation: Reg IV-positive neuroendocrine cells are associated with gastrin, serotonin, pancreatic polypeptide and somatostatin

We previously reported that Reg IV is associated with neuroendocrine (NE) differentiation in gastric cancers. The aim was to examine which NE hormone products are related to Reg IV-positive NE cells and their roles in gastric cancers. In the present study, we performed immunohistochemical analysis in a tissue microarray (TMA) of a consecutive series of 630 cases with ten different antibodies, including chromogranin A, synaptophysin and neural cell adhesion molecule (NCAM) as NE differentiation markers, and gastrin, serotonin, calcitonin, gastrin-releasing peptide (GRP), pancreatic polypeptide (PP), somatostatin and glucagon as NE hormones. In 630 cases, we identified 205 (33%) with NE differentiation and 147 (23%) positive for Reg IV. Reg IV-positive cases showed NE differentiation more frequently than Reg IV-negative cases (P < 0.0001). In 205 cases with NE differentiation, Reg IV-positive cases expressed serotonin (P= 0.0032) and somatostatin (P= 0.036) more frequently than Reg IV-negative cases. Double immunofluorescence staining revealed co-expression of Reg IV with gastrin, serotonin and PP. These results indicate that Reg IV might be a mediating factor of several NE hormones.

The role of Cdx2 in Barrett's metaplasia

Metaplasia (or transdifferentiation) is defined as the transformation of one tissue type to another. Clues to the molecular mechanisms that control the development of metaplasia are implied from knowledge of the transcription factors that specify tissue identity during normal embryonic development. Barrett's metaplasia describes the development of a columnar/intestinal phenotype in the squamous oesophageal epithelium and is the major risk factor for oesophageal adenocarcinoma. This particular type of cancer has a rapidly rising incidence and a dismal prognosis. The homoeotic transcription factor Cdx2 (Caudal-type homeobox 2) has been implicated as a master switch gene for intestine and therefore for Barrett's metaplasia. Normally, Cdx2 expression is restricted to the epithelium of the small and large intestine. Loss of Cdx2 function, or conditional deletion in the intestine, results in replacement of intestinal cells with a stratified squamous phenotype. In addition, Cdx2 is sufficient to provoke intestinal metaplasia in the stomach. In the present paper, we review the evidence for the role of Cdx2 in the development of Barrett's metaplasia.

Hepatocyte nuclear factor 1alpha and beta control terminal differentiation and cell fate commitment in the gut epithelium

The intestinal epithelium is a complex system characterized by massive and continuous cell renewal and differentiation. In this context, cell-type-specific transcription factors are thought to play a crucial role by modulating specific transcription networks and signalling pathways. Hnf1alpha and beta are closely related atypical homeoprotein transcription factors expressed in several epithelia, including the gut. With the use of a conditional inactivation system, we generated mice in which Hnf1b is specifically inactivated in the intestinal epithelium on a wild-type or Hnf1a(-/-) genetic background. Whereas the inactivation of Hnf1a or Hnf1b alone did not lead to any major intestinal dysfunction, the concomitant inactivation of both genes resulted in a lethal phenotype. Double-mutant animals had defective differentiation and cell fate commitment. The expression levels of markers of all the differentiated cell types, both enterocytes and secretory cells, were affected. In addition, the number of goblet cells was increased, whereas mature Paneth cells were missing. At the molecular level, we show that Hnf1alpha and beta act upstream of the Notch pathway controlling directly the expression of two crucial components: Jag1 and Atoh1. We demonstrate that the double-mutant mice present with a defect in intestinal water absorption and that Hnf1alpha and beta directly control the expression of Slc26a3, a gene whose mutations are associated with chloride diarrhoea in human patients. Our study identifies new direct target genes of the Hnf1 transcription factors and shows that they play crucial roles in both defining cell fate and controlling terminal functions in the gut epithelium.

An FGF4-FRS2alpha-Cdx2 axis in trophoblast stem cells induces Bmp4 to regulate proper growth of early mouse embryos

A variety of stem cells are controlled by the actions of multiple growth factors in vitro. However, it remains largely unclear how growth factors control the proliferation and differentiation of stem cells in vivo. Here, we describe a novel paracrine mechanism for regulating a stem cell niche in early mammalian embryos, which involves communication between the inner cell mass (ICM) and the trophectoderm, from which embryonic stem (ES) cells and trophoblast stem (TS) cells can be derived, respectively. It is known that ES cells produce fibroblast growth factor (FGF)4 and that TS cells produce bone morphogenetic protein (Bmp)4. We provide evidence that FRS2alpha mediates activation of the extracellular signal-regulated progein kinase (ERK) pathway to enhance expression of transcription factor Cdx2 in TS cells in response to FGF4. Cdx2 in turn binds to an FGF4-responsive enhancer element of the promoter region of Bmp4, leading to production and secretion of Bmp4. Moreover, exogenous Bmp4 is able to rescue the defective growth of Frs2alpha-null ICM. These findings suggest an important role of Cdx2 for production of Bmp4 in TS cells to promote the proper growth of early mouse embryos.

The molecular pathogenesis of Barrett's esophagus: common signaling pathways in embryogenesis metaplasia and neoplasia

Although Barrett's esophagus has been recognized for over 50 years, the cellular and molecular mechanisms leading to the replacement of squamous esophageal epithelium with a columnar type are largely unknown. Barrett's is known to be an acquired process secondary to chronic gastroesophageal reflux disease and occurs in the presence of severe disruption of the gastroesophageal barrier and reflux of a mixture of gastric and duodenal content. Current hypothesis suggest that epithelial change occurs due to stimulation of esophageal stem cells present in the basal layers of the epithelium or submucosal glands, toward a columnar epithelial differentiation pathway. The transcription factor CDX2 seems to play a key role in promoting the cellular biology necessary for columnar differentiation, and can be induced by bile salt and acid stimulation. Several cellular signaling pathways responsible for modulation of intestinal differentiation have also been identified and include WNT, Notch, BMP, Sonic HH and TGFB. These also have been shown to respond to stimulation by bile acids, acid or both and may influence CDX2 expression. Their relative activity within the stem cell population is almost certainly responsible for the development of the esophageal columnar epithelial phenotype we know as Barrett's esophagus.

Expression of resistin-like molecule beta in Barrett's esophagus: a novel biomarker for metaplastic epithelium

The formation of goblet cells characterizes the intestinal metaplasia of Barrett's esophagus (BE). Hematoxylin-eosin (HE) staining may fail to show intestinal metaplasia in BE, and PAS-Alcian Blue may present difficulties of interpretation due to its more heterogeneous staining. Recent evidence indicates that expression of resistin-like molecule beta (RELMbeta), a goblet cell-specific protein, is uniquely restricted to intestinal epithelium. However, it still remains largely unknown whether RELMbeta can be served as a biomarker for metaplastic epithelium of BE. In this study, 104 biopsy specimens of the distal esophagus from 88 suspected BE patients were collected, including 56 suspected intestinal metaplasia, 26 gastric type mucosa, and 22 squamous epithelium. We evaluated the RELMbeta expression in these biopsy specimens, and compared with those of CDX-2 immunostaining and PAS-Alcian Blue staining (pH 2.5). Of the suspected intestinal metaplasia specimens, 46 presented intestinal-type goblet cells and were immunostaining positive for RELMbeta and CDX-2, the remaining ten possessed only goblet cell mimickers and were not reactive with RELMbeta and CDX-2. Of the gastric-type mucosa specimens, none reacted with either RELMbeta or CDX-2. Moreover, the squamous epithelium was not reactive with RELMbeta and CDX-2. Acid mucin was present in goblet cells in all cases of BE and columnar cells in ten gastric specimens. In addition, the reactivity of RELMbeta was enhanced in six BE specimens with dysplasia. These results provide evidence that RELMbeta protein may be a novel biomarker to distinguish the intestinal-type goblet cells and goblet cell mimickers, and useful in the correct diagnosis of BE.

Cdx genes, inflammation, and the pathogenesis of intestinal metaplasia

Intestinal metaplasia (IM) is a biologically interesting and clinically relevant condition in which one differentiated type of epithelium is replaced by another that is morphologically similar to normal intestinal epithelium. Two classic examples of this are gastric IM and Barrett's esophagus (BE). In both, a chronic inflammatory microenvironment, provoked either by Helicobacter pylori infection of the stomach or acid and bile reflux into the esophagus, precedes the metaplasia. The Caudal-related homeodomain transcription factors Cdx1 and Cdx2 are critical regulators of the normal intestinal epithelial cell phenotype. Ectopic expression of Cdx1 and Cdx2 occurs in both gastric IM as well as in BE. This expression precedes the onset of the metaplasia and implies a causal role for these factors in this process. We review the observations regarding the role of chronic inflammation and the Cdx transcription factors in the pathogenesis of gastric IM and BE.

Selective activation of tumor growth-promoting Ca2+ channel MS4A12 in colon cancer by caudal type homeobox transcription factor CDX2

Colon cancer-associated MS4A12 is a novel colon-specific component of store-operated Ca²⁺ (SOC) entry sensitizing cells for epidermal growth factor (EGF)-mediated effects on proliferation and chemotaxis. In the present study, we investigated regulation of the MS4A12 promoter to understand the mechanisms responsible for strict transcriptional restriction of this gene to the colonic epithelial cell lineage. DNA-binding assays and luciferase reporter assays showed that MS4A12 promoter activity is governed by a single CDX homeobox transcription factor binding element. RNA interference (RNAi)-mediated silencing of intestine-specific transcription factors CDX1 and CDX2 and chromatin immunoprecipitation (ChIP) in LoVo and SW48 colon cancer cells revealed that MS4A12 transcript and protein expression is essentially dependent on the presence of endogenous CDX2. In summary, our findings provide a rationale for colon-specific expression of MS4A12. Moreover, this is the first report establishing CDX2 as transactivator of tumor growth-promoting gene expression in colon cancer, adding to untangle the complex and conflicting biological functions of CDX2 in colon cancer and supporting MS4A12 as important factor for normal colonic development as well as for the biology and treatment of colon cancer.

Immunohistochemical staining for P1 and P2 promoter-driven hepatocyte nuclear factor-4alpha may complement mucin phenotype of differentiated-type early gastric carcinoma

Hepatocyte nuclear factor 4alpha (HNF4alpha) isoforms in the human stomach have not been fully investigated. The purpose of the present study was to evaluate the expression of P1 and P2 promoter-driven HNF4alpha (P1 and P2-HNF4alpha) in differentiated-type early gastric carcinomas (DEGC). P1- and P2-HNF4alpha expression was examined immunohistochemically both in non-neoplastic mucosa and carcinoma from surgical specimens. In all samples of non-neoplastic mucosa, foveolar, cardiac, fundic and pyloric gland epithelium was negative for P1-HNF4alpha, but was positive for P2-HNF4alpha. Intestinal metaplasia was positive for P1 and P2-HNF4alpha in all cases. Gastric carcinomas were classified into four mucin phenotypes based on the pattern of mucin expression: gastric, intestinal, mixed and null type. DEGC showed striking differences in the staining pattern for P1-HNF4alpha according to the mucin phenotype. Gastric carcinomas of intestinal, mixed and null type showed high positivity for P1-HNF4alpha, but the gastric type was negative for P1-HNF4alpha in all but one tumor. In contrast, P2-HNF4alpha was expressed in all tumors regardless of the mucin phenotype. Negative expression of P1-HNF4alpha was indicated as one of the useful immunohistochemical markers in the classification of mucin phenotype of both non-neoplastic mucosa and cancers of gastric phenotype.

Inhibition of nucleostemin upregulates CDX2 expression in HT29 cells in response to bile acid exposure: implications in the pathogenesis of Barrett's esophagus

BACKGROUND

Barrett's esophagus (BE), a squamous-to-columnar metaplasia, may originate from growth-promoting mutations in metaplastic stem cells. Nucleostemin is a protein highly expressed in undifferentiated embryonic stem cells. The objectives of this study were to explore the potential role of nucleostemin in the pathogenesis of BE METHODS: The expression profiles of 30,968 genes were compared between BE and normal esophageal tissues (n = 6 in each group) by using oligo microarray. Three siRNA plasmid expression vectors against nucleostemin, pRNAi-1, pRNAi-2, and pRNAi-3, were constructed and transfected into HT29 cells. In addition, HT29 cells were exposed to 100-1,000 microM chenodeoxycholic acid (CDC), a bile acid, for 2, 12, and 24 h, and then messenger RNA and protein expressions of nucleostemin and CDX2 were determined by reverse-transcriptase polymerase chain reaction and Western blotting.

RESULTS

Four hundred and twenty-six differentially expressed genes were detected in BE; 142 were upregulated and 284 downregulated. Nucleostemin was downregulated while CDX2 was upregulated. In vitro, all the recombinant plasmids inhibited the nucleostemin expression in transfected HT29 cells, with pRNAi-1 being the most effective. CDX2 expression was significantly increased in pRNAi-1-transfected HT29 cells, compared with that in the empty plasmid (pRNAT-U6.1/Neo) transfected or untransfected HT29 cells. In addition, CDX2 expression was increased whereas nucleostemin expression was decreased in a dose- and time-dependent manner in HT29 cells treated with CDC.

CONCLUSION

These findings suggest that the inhibition of nucleostemin expression in "esophageal stem cells" in response to bile acid exposure may be involved in the pathogenesis of BE through upregulating CDX2 expression.

Intrauterine growth restriction alters postnatal colonic barrier maturation in rats

Intrauterine growth restriction (IUGR) is a leading cause of perinatal mortality and morbidity and increases the risk for necrotizing enterocolitis. We hypothesized that colonic barrier disruption could be responsible for intestinal frailty in infants and adults born with IUGR. Mucins and trefoil factor family 3 (TFF3) actively contribute to epithelium protection and healing. Our aim was to determine whether IUGR affects colonic mucosa maturation. IUGR was induced by dietary protein restriction in pregnant dams. Mucins and Tff3 expression and morphologic maturation of the colonic mucosa were followed during postnatal development of the offspring. Before weaning, mucin 2 and Tff3 protein levels were reduced in colonic mucosa of rats with IUGR compared with controls. After weaning, expression of mucin 2 (mRNA and protein) and mucin 4 (mRNA) were lower in colonic mucosa of rats with IUGR. At the same time, IUGR was associated with a reduction of crypt depth and a higher percentage of crypts in fission. We conclude that IUGR impairs mucus barrier development and is associated with long-term alterations of mucin expression. The lack of an efficient colonic barrier induced by IUGR may predispose to colonic injury not only in neonatal life but also in later life.

Juvenile polyps have gastric differentiation with MUC5AC expression and downregulation of CDX2 and SMAD4

CDX2 is a homeobox transcription factor that works as a master gene in intestinal differentiation, both in the colon and in aberrant locations such as intestinal metaplasia (IM) of the stomach. Transgenic mice with Cdx2 expression in the stomach develop IM and Cdx2(+/-) mice develop hamartomatous polyps in the colon presenting gastric differentiation. We previously observed regulation of CDX2 by the BMP/SMAD pathway in the gastric context. Here, we hypothesized that juvenile polyps, which are hamartomatous polyps caused by mutations in members of the BMP/SMAD pathway, might recapitulate the gastric differentiation observed in Cdx2(+/-) mice due to SMAD4 and CDX2 downregulation. We characterized SMAD4 and CDX2 expression in a series of 18 solitary juvenile polyps and 2 polyps from juvenile polyposis (JP) patients, one with a germline SMAD4 mutation and one with a germline BMPRIA mutation, as well as the expression of an intestinal differentiation marker, MUC2 (by immunohistochemistry and in situ hybridization), and gastric differentiation markers, MUC5AC and MUC6 (by immunohistochemistry). We observed that juvenile polyps have a heterogeneous expression of CDX2, MUC2 and SMAD4, with negative areas, and 15 of the 18 solitary polyps and the JP case with SMAD4 mutation exhibit de novo expression of MUC5AC but not MUC6. In conclusion, juvenile polyps have gastric transdifferentiation associated with downregulation of CDX2 and SMAD4, lending support to the role of the BMP/SMAD pathway in CDX2 regulation.

Intratumoural heterogeneity of intestinal expression reflects environmental induction and progression-related loss of induction in undifferentiated-type gastric carcinomas

AIMS

Gene expression in tumours is regulated by environmental as well as genetic/epigenetic factors. This study assessed the environmental factors in intestinal expression of gastric cancers.

METHODS AND RESULTS

We immunohistochemically examined intratumoural heterogeneity in the expression of Cdx2, MUC2, MUC5AC and MUC6 in 39 intramucosal and 49 extramucosally invasive undifferentiated-type gastric carcinomas (UGCs), consisting of signet ring cell carcinomas showing a layered structure (LS) in the mucosa and dedifferentiated tubular adenocarcinomas without LS and with minor tubular components (TC). The LS retains mucosal vertical polarity with superficial MUC5AC expression. Loss of this polarity was independent of intestinal expression and associated with extramucosal invasion. In LS(+) UGCs, intestinal expression was enhanced as the size of mucosal spread increased and was significantly reduced with deeper extramucosal invasion, whereas, in LS(-)/TC(+) UGCs, intestinal expression was frequent and predominant in the mucosa and was insignificantly reduced with deeper extramucosal invasion.

CONCLUSIONS

In LS(+) UGCs, intestinal expression showed dynamic alteration probably by environmental induction and progression-related loss of induction, whereas it was relatively stable in LS(-)/TC(+) UGCs. Thus, intestinal expression in UGCs is not useful as a marker of tumour progression because it is also affected by environmental factors and genetic lineage.

Gastrointestinal differentiation marker Cytokeratin 20 is regulated by homeobox gene CDX1

CDX1 is a transcription factor that plays a key role in intestinal development and differentiation. However, the downstream targets of CDX1 are less well defined than those of its close homologue, CDX2. We report here the identification of downstream targets of CDX1 using microarray gene-expression analysis and other approaches. Keratin 20 (KRT20), a member of the intermediate filament and a well-known marker of intestinal differentiation, was initially identified as one of the genes likely to be directly regulated by CDX1. CDX1 and KRT20 mRNA expression were significantly correlated in a panel of 38 colorectal cancer cell lines. Deletion and mutation analysis of the KRT20 promoter showed that the minimum regulatory region for the control of KRT20 expression by CDX1 is within 246 bp upstream of the KRT20 transcription start site. ChIP analysis confirmed that CDX1 binds to the predicted CDX elements in this region of the KRT20 promoter in vivo. In addition, immunohistochemistry showed expression of CDX1 parallels that of KRT20 in the normal crypt, which further supports their close relationship. In summary, our observations strongly imply that KRT20 is directly regulated by CDX1, and therefore suggest a role for CDX1 in maintaining differentiation in intestinal epithelial cells. Because a key feature of the development of a cancer is an unbalanced program of proliferation and differentiation, dysregulation of CDX1 may be an advantage for the development of a colorectal carcinoma. This could, therefore, explain the relatively frequent down regulation of CDX1 in colorectal carcinomas by hypermethylation.

Enhanced expression of resistin-like molecule beta in human colon cancer and its clinical significance

Previous studies have indicated that resistin-like molecule beta (RELM beta), an intestinal goblet cell-specific protein, is markedly increased in the intestinal tumors of min mice and over-expressed in a human colon cancer cell line. We hypothesized that RELM beta might be enhanced in human colon cancer. The aim of this study was to examine the clinical importance of RELM beta expression in colon cancer patients and to correlate its expression with various clinicopathological parameters, upstream regulatory molecule expression, tumor proliferative capacity, and patients' survival. Of the 80 colon cancer patients studied, 65 (81.25%) tested positive for RELM beta, mainly in the cytoplasm of colon mucosa. Contrasting sharply with the strongly RELM beta-positive tumors, normal colon mucous membrane was negative or weakly positive. RELM beta positivity in colon cancer was correlated with histological grade of differentiation and lymph node metastasis, but not with age, gender, tumor location and size, tumor infiltration, Dukes' stage, liver metastasis, and venous invasion. RELM beta expression was significantly correlated with the expression of transcription factor CDX-2 (P < 0.01) but not with that of proliferative index Ki-67 (P > 0.05). The mean postoperative survival time (2.76 years) of RELM beta-positive patients was significantly longer than that (1.26 years) of RELM beta-negative patients (P = 0.032). These findings support evidence of the enhanced RELM beta expression in colon cancer patients and suggest that further investigation is warranted to explore the role of RELM beta in colon cancer.

Requirement of Notch activation during regeneration of the intestinal epithelia

Notch signaling regulates cell differentiation and proliferation, contributing to the maintenance of diverse tissues including the intestinal epithelia. However, its role in tissue regeneration is less understood. Here, we show that Notch signaling is activated in a greater number of intestinal epithelial cells in the inflamed mucosa of colitis. Inhibition of Notch activation in vivo using a gamma-secretase inhibitor resulted in a severe exacerbation of the colitis attributable to the loss of the regenerative response within the epithelial layer. Activation of Notch supported epithelial regeneration by suppressing goblet cell differentiation, but it also promoted cell proliferation, as shown in in vivo and in vitro studies. By utilizing tetracycline-dependent gene expression and microarray analysis, we identified a novel group of genes that are regulated downstream of Notch1 within intestinal epithelial cells, including PLA2G2A, an antimicrobial peptide secreted by Paneth cells. Finally, we show that these functions of activated Notch1 are present in the mucosa of ulcerative colitis, mediating cell proliferation, goblet cell depletion, and ectopic expression of PLA2G2A, thereby contributing to the regeneration of the damaged epithelia. This study showed the critical involvement of Notch signaling during intestinal tissue regeneration, regulating differentiation, proliferation, and antimicrobial response of the epithelial cells. Thus Notch signaling is a key intracellular molecular pathway for the proper reconstruction of the intestinal epithelia.

Deoxycholic acid induces the overexpression of intestinal mucin, MUC2, via NF-kB signaling pathway in human esophageal adenocarcinoma cells

Background

Mucin alterations are a common feature of esophageal neoplasia, and alterations in MUC2 mucin have been associated with tumor progression in the esophagus. Bile acids have been linked to esophageal adenocarcinoma and mucin secretion, but their effects on mucin gene expression in human esophageal adenocarcinoma cells is unknown.

Methods

Human esophageal adenocarcinoma cells were treated 18 hours with 50–300 μM deoxycholic acid, chenodeoxycholic acid, or taurocholic acid. MUC2 transcription was assayed using a MUC2 promoter reporter luciferase construct and MUC2 protein was assayed by Western blot analysis. Transcription Nuclear factor-κB activity was measured using a Nuclear factor-κB reporter construct and confirmed by Western blot analysis for Nuclear factor-κB p65.

Results

MUC2 transcription and MUC2 protein expression were increased four to five fold by bile acids in a time and dose-dependent manner with no effect on cell viability. Nuclear factor-κB activity was also increased. Treatment with the putative chemopreventive agent aspirin, which decreased Nuclear factor-κB activity, also decreased MUC2 transcription. Nuclear factor-κB p65 siRNA decreased MUC2 transcription, confirming the significance of Nuclear factor-κB in MUC2 induction by deoxycholic acid. Calphostin C, a specific inhibitor of protein kinase C (PKC), greatly decreased bile acid induced MUC2 transcription and Nuclear factor-κB activity, whereas inhibitors of MAP kinase had no effect.

Conclusion

Deoxycholic acid induced MUC2 overexpression in human esophageal adenocarcinoma cells by activation of Nuclear factor-κB transcription through a process involving PKC-dependent but not PKA, independent of activation of MAP kinase.

Tumor necrosis factor-alpha induces the aberrant expression of mucus core protein-2 in non-neoplastic biliary epithelial cells via the upregulation of CDX2 in chronic cholangitis

AIM

Chronic cholangitis, such as hepatolithiasis, is frequently associated with goblet cell metaplasia and the aberrant expression of mucus core protein-2 (MUC2). In this study, we clarified the role of inflammatory cytokines in the expression of MUC2 in lining biliary epithelial cells (BEC) in chronic cholangitis with an emphasis on CDX2, an intestine-specific transcription factor.

METHODS

We used human hepatolithiatic livers and polycystic kidney (PCK) rats, an animal model of Caroli's disease, and cultured BEC from PCK rats. As a control, extrahepatic biliary obstruction and histologically normal livers and Crj:CD rats were used.

RESULTS

Immunohistochemically, tumor necrosis factor-alpha (TNF-alpha) was expressed in periductal inflammatory cells and BEC of the affected intrahepatic bile ducts with an aberrant expression of MUC2 and CDX2 in hepatolithiasis and the PCK rats. In cultured BEC, TNF-alpha, interleukin (IL)-1beta, IL-6, and interferon-gamma induced the expression of CDX2 mRNA, though only TNF-alpha additionally induced the expression of MUC2 mRNA. The expression of CDX2 mRNA and the MUC2 protein induced in BEC by TNF-alpha were abolished by pretreatment of nuclear factor-kappaB inhibitors.

CONCLUSION

The aberrant expression of CDX2 and MUC2 in the affected bile ducts showing goblet cell metaplasia was closely associated with TNF-alpha expressed in periductal infiltrating inflammatory cells and BEC. TNF-alpha induced the expression of CDX2 and MUC2 in cultured BEC. Taken together, it seems likely that TNF-alpha plays a role in MUC2 expression via CDX2 upregulation in the bile ducts with chronic cholangitis and goblet cell metaplasia.

CaSR stimulates secretion of Wnt5a from colonic myofibroblasts to stimulate CDX2 and sucrase-isomaltase using Ror2 on intestinal epithelia

To understand whether extracellular calcium-sensing receptor (CaSR) expression on colonic myofibroblast cells (18Co) contributed to epithelial homeostasis, we activated the CaSR with 5 mM Ca(2+), screened by RT-PCR Wnt family members, and measured their secretion. Transcripts for Wnt 1, 2, 2b, 3a, 4, and 7a were either absent or unchanged whereas Wnt3 decreased and Wnt5a increased. We assessed Wnt5a secretion by Western blot. High Ca(2+) (5 mM) substantially increased Wnt5a secretion; small interfering RNA (siRNA) against the CaSR reduced this to constitutive amounts. Expression of Wnt5a plasmid but not Wnt1 or Wnt3a increased caudal homeodomain factor CDX2 transcripts and protein in HT-29 adenocarcinoma cells. Wnt5a increased activity of a sucrase-isomaltase (SI) promoter in Caco-2BBE cells. Wnt5a protein stimulation of CDX2 transcripts and protein and SI reporter were increased by overexpression of wild-type Ror2, a Wnt5a receptor, and reduced with siRNA against Ror2. CaSR activation of HT-29 cells increased Ror2 protein expression. Ror2 protein was expressed in mouse jejunum from crypt base to villus tip and in the colon on surface epithelia. Our results show that activation of a G protein-coupled receptor, the CaSR, stimulates secretion of Wnt5a from myofibroblasts. Stimulation of epithelia by the CaSR increased the expression of a receptor for Wnt5a, the tyrosine kinase Ror2, suggesting existence of a unique paracrine relationship for CDX2 homoeostasis in the intestine and revealing new contributions of CaSR-activated myofibroblasts to intestinal stem cell niche microenvironments.

Biology of intestinal metaplasia in 2008: more than a simple phenotypic alteration

This review concentrates on one main aspect of cancerization in the oesophagus and stomach: principally, intestinal metaplasia. There are at least two other important pathways that lead to cancer and do not need such a morphological transformation. One is the gastric type of carcinoma on the Lauren classification, which arises directly from the stem cell zone and is the signet ring form of cancer, while the other is spasmolytic polypeptide-expressing metaplasia (SPEM)--spasmolytic polypeptide (TFF2) expressing metaplasia, where the gastric glands become filled with TFF2-expressing cells and may also lead to gastric dysplasia and cancer. The development of intestinal metaplasia is complex. Here, we examine intestinal metaplasia in molecular terms, noting the over-expression of Cdx1, Cdx2, Pdx1, Oct1, TFF3 and the downregulation of Hedgehog signalling; Runx3 is deactivated by epigenetic silencing, and pathways such as Wnt and MARK/ERK are involved. These changes start to explain the principles of the development of intestinal metaplasia and suggest that the regulation of these genes is of importance in the development of gastric cancer.

Cytokeratin and CDX-2 expression in Barrett's esophagus

OBJECTIVE

Barrett's esophagus (BE) is a premalignant condition of the distal esophagus. For diagnostic purposes it is important to find biomarkers that can specifically identify BE, for instance to differentiate BE epithelial cells from gastric cardia epithelial cells in brush cytology specimens. The objective of this study was to determine the specificity of CDX-2 and a set of cytokeratins (CKs) as specific markers for BE as compared with normal squamous esophageal and gastric cardia tissue.

MATERIAL AND METHODS

Immunohistochemistry (IHC) with specific antibodies against CDX-2, and a set of CKs was performed on fresh frozen consecutive tissue sections of normal squamous, gastric cardia and non-dysplastic BE of 80 patients.

RESULTS

IHC results showed CK8, CK18 and CK20 expression in both BE and gastric cardia, while CK7 was seen in all BE but also in 26% of gastric cardia biopsies. CK10/13 was only expressed in normal squamous epithelium. CDX-2 nuclear staining was found in 87.5% of the BE biopsies, whereas normal squamous esophagus and cardia biopsies were negative.

CONCLUSIONS

CDX-2 in combination with a set of CKs can be used as biomarkers to distinguish between BE and normal squamous esophagus. In order to distinguish BE from cardia tissue, a combination of CDX-2 and CK7 is most informative.

Homeoprotein Cdx2 and nuclear PTEN expression profiles are related to gastric cancer prognosis

The aim of the study was to analyze the expression of Cdx2 and nuclear PTEN in relation to clinicopathological features of gastric cancer tissue biopsies in order to determine the value of a combined analysis of Cdx2 and nuclear PTEN expression in distinguishing histological types and prognosis of gastric cancers. The expression of Cdx2 and nuclear PTEN was studied using immunohistochemistry of paraffin-embedded tumor specimens from 99 patients who underwent radical D2 gastrectomy between 1999 and 2001. Cdx2 and nuclear PTEN expression were detected in 39.6% (36 of 91) and 70.3% (64 of 91) of gastric cancer cases, respectively. There was a negative correlation between Cdx2 expression and Lauren classification (p=0.032), and between nuclear PTEN expression and lymph node metastasis (p=0.049). Patients with Cdx2-positive, or nuclear PTEN-positive expression had higher survival rates than those with Cdx2-negative or nuclear PTEN-negative expression (p<0.001 and p=0.003, respectively). Co-expression of Cdx2 and nuclear PTEN showed significantly lower levels in diffuse- or mixed-type cancers than in intestinal-type cancers (p=0.005). Multivariate analysis revealed that Cdx2 expression was an independent prognostic indicator of gastric cancer (p=0.014). These data suggest that combined analysis of Cdx2 and nuclear PTEN expression can have significant value in distinguishing histological types of gastric cancer and assessing prognosis in patients with gastric cancer.

The homeodomain transcription factor Cdx1 does not behave as an oncogene in normal mouse intestine

The Caudal-related homeobox genes Cdx1 and Cdx2 are intestine-specific transcription factors that regulate differentiation of intestinal cell types. Previously, we have shown Cdx1 to be antiproliferative and to promote cell differentiation. However, other studies have suggested that Cdx1 may be an oncogene. To test for oncogenic behavior, we used the murine villin promoter to ectopically express Cdx1 in the small intestinal villi and colonic surface epithelium. No changes in intestinal architecture, cell differentiation, or lineage selection were observed with expression of the transgene. Classic oncogenes enhance proliferation and induce tumors when ectopically expressed. However, the Cdx1 transgene neither altered intestinal proliferation nor induced spontaneous intestinal tumors. In a murine model for colitis-associated cancer, the Cdx1 transgene decreased, rather than increased, the number of adenomas that developed. In the polyps, the expression of the endogenous and the transgenic Cdx1 proteins was largely absent, whereas endogenous Villin expression was retained. This suggests that transgene silencing was specific and not due to a general Villin inactivation. In conclusion, neither the ectopic expression of Cdx1 was associated with changes in intestinal cell proliferation or differentiation nor was there increased intestinal cancer susceptibility. Our results therefore suggest that Cdx1 is not an oncogene in normal intestinal epithelium.

Proteasomal degradation of Atoh1 by aberrant Wnt signaling maintains the undifferentiated state of colon cancer

Atoh1 plays a crucial role in intestinal cell differentiation. We have demonstrated that its human homolog Hath1 protein is targeted by the Wnt-GSK3 axis, resulting in the proteasomal degradation in human colon cancer. However, the contribution of Hath1 degradation to the undifferentiated state of colon cancer remains unknown. In this study, we demonstrated that both constitutive expression of mutant Hath1 and stabilization of Hath1 protein by a GSK3 inhibitor in colon cancer cells increased the expression of MUC2 known as a representative function of differentiated goblet cells. This means that Hath1 protein degradation may be required for maintaining the undifferentiated state of colon cancers, and that GSK3 inhibitors have potential for use in cancer therapy.

Quantitative analysis of the effect of Helicobacter pylori on the expressions of SOX2, CDX2, MUC2, MUC5AC, MUC6, TFF1, TFF2, and TFF3 mRNAs in human gastric carcinoma cells

OBJECTIVE

To investigate the phenotypic characters of carcinoma cells and the response of gastric epithelial cells to Helicobacter pylori (H. pylori) infection using the gastric carcinoma cell lines.

MATERIAL AND METHODS

Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to assess the effect of H. pylori infection on mRNA levels of transcription factors (SOX2 and CDX2), mucin core proteins (MUC2, MUC5AC, and MUC6), and trefoil factor family peptides (TFF) (TFF1, TFF2, and TFF3) in gastric carcinoma cells (AGS, MKN45, and KATO III cells). H. pylori ATCC 43504 and its isogenic cag pathogenicity island (PAI) deleted mutant were used.

RESULTS

These cell lines expressed mixed gastric and intestinal phenotypes. The intestinal phenotype predominated in AGS cells and gastric phenotypes in MKN45 and KATO III cells. In all three cell lines, H. pylori infection inhibited SOX2 mRNA expression, but induced the three TFFs mRNAs. In AGS cells, H. pylori induced cag PAI-dependent mRNA expression of CDX2, MUC2, MUC5AC, and MUC6. mRNA expressions of CDX2, MUC5AC, and MUC6 were inhibited in KATO III cells, whereas MUC2 mRNA expression was unchanged. In MKN45 cells, H. pylori induced the three MUCs mRNAs but inhibited CDX2 mRNA expression.

CONCLUSIONS

This study provides a useful platform for selecting appropriate cell lines to model H. pylori-related changes in the gastric epithelium that mirror the changes seen in vivo. The outcome of H. pylori infection may reflect changes in the mucus gel layer caused by altered expression of mucins and TFF peptides.

Mucins in the mucosal barrier to infection

The mucosal tissues of the gastrointestinal, respiratory, reproductive, and urinary tracts, and the surface of the eye present an enormous surface area to the exterior environment. All of these tissues are covered with resident microbial flora, which vary considerably in composition and complexity. Mucosal tissues represent the site of infection or route of access for the majority of viruses, bacteria, yeast, protozoa, and multicellular parasites that cause human disease. Mucin glycoproteins are secreted in large quantities by mucosal epithelia, and cell surface mucins are a prominent feature of the apical glycocalyx of all mucosal epithelia. In this review, we highlight the central role played by mucins in accommodating the resident commensal flora and limiting infectious disease, interplay between underlying innate and adaptive immunity and mucins, and the strategies used by successful mucosal pathogens to subvert or avoid the mucin barrier, with a particular focus on bacteria.